Created macOS (markdown)

Webb Phillips 2022-03-04 19:38:19 +01:00
parent 65f17f64da
commit 44bc02fafb

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macOS.md Normal file

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Note: all commands below are to be executed as the root user.
1. Re-generate the RSA and ED25519 keys
```
rm /etc/ssh/ssh_host_*
ssh-keygen -t rsa -b 4096 -f /etc/ssh/ssh_host_rsa_key -N ""
ssh-keygen -t ed25519 -f /etc/ssh/ssh_host_ed25519_key -N ""
```
2. Remove small Diffie-Hellman moduli
```
awk '$5 >= 3071' /etc/ssh/moduli > /etc/ssh/moduli.safe
mv /etc/ssh/moduli.safe /etc/ssh/moduli
```
3. Enable the RSA and ED25519 keys
Enable the RSA and ED25519 HostKey directives in the /etc/ssh/sshd_config file:
```
sed -i 's/^\#HostKey \/etc\/ssh\/ssh_host_\(rsa\|ed25519\)_key$/HostKey \/etc\/ssh\/ssh_host_\1_key/g' /etc/ssh/sshd_config
```
4. Restrict supported key exchange, cipher, and MAC algorithms
```
echo '
# Restrict key exchange, cipher, and MAC algorithms, as per sshaudit.com
# hardening guide.
KexAlgorithms curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha256
Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr
MACs hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,umac-128-etm@openssh.com
HostKeyAlgorithms ssh-ed25519,rsa-sha2-512,rsa-sha2-256' >> /etc/sshd/sshd_config
```
5. Restart OpenSSH server
```
sudo launchctl stop com.openssh.sshd
```